They are only staying on in the country to seek justice for their family, they say.
Earlier this month, a Year 9 Ashburton College student was left with a fractured eye socket, neck injury and concussion after being allegedly assaulted in class by another student.
The boy's mother, who has asked to be known as Nandita, said the family was under huge stress because they had been working under the Accredited Employment Work Scheme, but left their jobs two months ago because she claims they were being exploited.
She said she and her husband had lodged a complaint with the Ministry of Business, Innovation and Employment, and had received a migrant exploitation protection visa while the ministry looked into their case.
Such visas are issued if the ministry is satisfied that it is credible that exploitation may have occurred.
Nandita said she never imagined they would go through what they had when they came to New Zealand.
She said now she just wanted to get justice for her and her husband, and for her son.
She claims she was paid only $15 an hour - the minimum adult wage is $23.15 - and said she was bullied in her job.
Nandita has declined to name her previous employer and therefore RNZ is unable to seek comment from them.
She claims about 400 hours' worth of pay was also withheld from her and her husband, who worked for the same company.
When she left the job, she said her and family were also kicked out of their rental property because the owner of the rental was connected to their employer.
A Givealittle page has been set up to help the family.
Nandita said her son was also still suffering badly from the attack and was a long way off from being able to return to school.
She still had not been told what action would be taken against the boy who injured her son by the school or the police.
Ashburton College has not responded to inquiries from RNZ.
Nandita said she was very grateful for the help her family had received in Ashburton from Safer Mid Canterbury, the Salvation Army and St Vincent de Paul.
Immigration New Zealand national manager investigations Jason Perry confirmed that Nandita was granted a migrant exploitation protection work visa in July.
He said the visa enabled migrants with supported work visas to leave their job quickly while allegations of exploitation were being investigated.
Immigration New Zealand had received one complaint in relation to Nandita's previous employer, he said.
To protect the identity of the process, he was unable to provide any further detail as doing so may compromise any investigation or future investigation, he said.
